Electrooxidation of Hydrazine Utilizing High-Entropy Alloys: Assisting the Oxygen Evolution Reaction at the Thermodynamic Voltage

Katiyar, NK and Dhakar, S and Parui, A and Gakhad, P and Singh, AK and Biswas, K and Tiwary, CS and Sharma, S (2021) Electrooxidation of Hydrazine Utilizing High-Entropy Alloys: Assisting the Oxygen Evolution Reaction at the Thermodynamic Voltage. In: ACS Catalysis . pp. 14000-14007.

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Abstract

Hydrazine electrooxidation is an important reaction as it assists in decreasing the OER overvoltage. Herein, we report the utilization of a high-entropy nanocatalyst alloy for the electrooxidation of hydrazine. The high-entropy nanocatalyst comprising five elements (Ag, Au, Pt, Pd, Cu) shows profound activity toward this molecule at a low overvoltage. An intriguingly high-entropy nanocatalyst prepared by the casting-cum-cryomilling method is endowed with the unique catalytic activity for the HzOR. A detailed analysis of gaseous product points to the formation of nitrogen as well as oxygen as the oxidation product, a sign of accompanying the oxygen evolution reaction (OER). Interestingly, a significant amount of oxygen is detected at 1.13 V (reversible hydrogen electrode (RHE)) in a neutral buffered medium, confirming that the OER is functional at a voltage near the thermodynamic voltage of 1.23 V (RHE). The quantitative contribution of each hydrazine and OER is ascertained, which explains a vital insight into this reaction. Density functional theory calculations showed that both HzOR and OER assist each other where the electron-donating effect of H2O to the surface can reduce the endothermicity of the HzOR. However, the electron acceptance of*NHNH2 helps in a favorable overlap of the HEA Fermi level and vacant states with the HOMO of H2O. ©

Item Type:	Journal Article
Publication:	ACS Catalysis
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society
Keywords:	Catalyst activity; Density functional theory; Electrooxidation; Entropy; Hydrazine; Nanocatalysts; Oxygen, Electrooxidations; Element ag; High entropy alloys; Hydrazine oxidation; Low overvoltage; Microscopy analyse; Nano-catalyst; Nanocatalysis; Over-voltages; Reversible hydrogen electrodes, Electrolysis
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	03 Dec 2021 08:54
Last Modified:	03 Dec 2021 08:54
URI:	http://eprints.iisc.ac.in/id/eprint/70650

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